body {
    background: #222;
    overflow: hidden;
}
i {
    position: absolute;
    width: 4px;
    height: 4px;
    background: #0f0;
    pointer-events: none;
    animation: animate 2s linear forwards;
}
@keyframes animate {
    0% {
        opacity: 1;
        transform: translate(0,0);
    }
    100% {
        opacity: 0;
        transform: translate(var(--x), var(--y));
    }
}